I've been perusing a lighting textbook I found recently and it mentions a box of three 3" fresnels controlled by household fixture dimmers that can be used to experiment with different colors and how they mix. I've been looking into building one myself, but the cheapest I've seen the fresnels for was about $100 each which is a bit out of the price range of a mostly jobless high school student. Are there cheaper fixtures I can find for this kind of thing? Am I looking in the wrong places for these fixtures? Does this even sound safe (this book was from the early 90s so it's possible things have changed regarding this kind of contraption)?